Download - Structure (Plasma Membrane) A lipid bilayer(2 layers of lipids) with a variety of proteins
Structure(Plasma Membrane)
A lipid bilayer(2 layers of lipids) with a variety of proteins
Lipid molecule
Proteins
Identify the lipid molecules.Identify the protein molecules.
What is a ‘lipid bilayer’?
Function
-To be Selective Permeable: =control what passes in or out of the cell
(Plasma Membrane)
-Helps maintain Homeostasis: = maintain a stable internal environment
-Act as a lining, separates the chemicals of the cytoplasm from the surroundings
What the lipids do…
(Plasma Membrane)
. 1. Form a. open channels b. gated channels
c. active transport pathways,All to move molecules in & out
of the cell!
What the proteins do…
Open channels
Ex. 1 of channel proteins.
Gated channel
Ex. 2 of channel proteins.
(Plasma Membrane)
-Receptors that change cellular activity.
Protein Function #2
Receptor protein
Signal molecule
Change cellular activity
(Plasma Membrane)
-Create a molecular mark (signature) that identifies that specific, individual cell.
Protein Function #3
Recognition protein
LOOK!
Types of particle that might cross membranes.
Tiny molecules, like…
WaterOxygen& Carbon dioxide
Types of particle that might cross membranes.
Small molecules, like…
Glucose, amino acids, fatty acids and glycerol
Water Carbon Dioxide
Oxygen
Aminoacid
Glycerol GlucoseFatty Acid
Yet more types of particles that might cross
cell membranes!Yes, even large molecules,
such as…
PolysaccharidesLipids & proteins!
Lipid soluble molecules
Fats,Fatty acids
Charged particles
ions
Na+, K+, Cl+
Even Large Particles may sometimes cross the selectively
permeable cell membrane!
Such as…small organisms and Organic debris
DiffusionMovement of particles from an area of high
concentration to an area of lower concentration.
Diffusion requires a Concentration
gradientWhen the
concentration of particles is not the same throughout a
mixture.
Concentration Gradient
There is a region of high concentration and
a region of low concentration.
Go to page 7 in the note packet and
learn about the use of square brackets.
[ ]
Do the activity The Tea Cup
& The Swimming Pool
on page 8.
EquilibriumWhen the concentration
of particles is the same throughout a mixture.
EquilibriumThere is no region of high, nor a region of low concentration of
particles.
EquilibriumAll particle continue to
move.
Diffusion
Concentrationgradient
Equilibrium
TRANSPORTThe Movement of
Materials
Across Membranes
PassiveTransport
Materials move down the concentration
gradient and across a membrane.
What determines if a particle can go through a channel?
Dialysis Tubing
OsmosisThe passive
transport of water across a membrane.
Thistle Tube Demo
watermolasses
thistle tube
Selectively permeable membrane
Active TransportParticles move
•Across a SPM.•Against the concentration gradient.
•The cells must spend energy.
Active transport allows particles to move against the
concentration gradient.(from an area of _____
concentration to an area of ___ concentration)HIGH
LOW
An exampleof Active Transport:
All animal cells have a Sodium Potassium pump that pumps sodium (Na+) to the outside of cells and potassium (K+) to the inside of cells.
This ‘pump’ allows nerve cells to carry electrical messages through the
body!
+ + + + + + + + + - - - - - - - - - - - - - - - - -
Nerve cell
The Cell Membrane of a nerve cell
EndocytosisParticles move INTO the cell by folding a portion of the membrane around a particle, resulting in a vesicle.
There are two types of Endocytosis:
Pinocytosis - drinkingDissolved materials
Phagocytosis - eatingFood particles
Pinocytosis
The solute particles are too small to see but too big to pass through the membrane.
ExocytosisParticles move OUT OF a cell by fusing vesicles with the cell membrane.
Maintaining water balance
in Protists
Facilitated Transport(Facilitated Diffusion)
-Diffusion using protein channels
Transport protein
Gated channel
The End